Mechanical fuel pump



April l25, 1933.

F. G.V SCHWEISTHAL MECHANICAL FUEL PUMP Filed Deo. 2l, 1931 s sheets-sheet 1 y InUeTZJT: [76d @5c/201m@ April 25, 1933. F. G. scHwElsTHAL 1,905,246

MECHANICAL FUEL PUMP Filed Dec. 21, 1931 3 Sheiets-Sheet 2 April 25, 1933.

MECHANICAL FUEL PUMP Filed Dec. 21, 1931 3' sheets-sheet 5' ed a @www F.,G. scHwElSTHAL 1,905,246

45 taken on the Patented. Apr. 25, l19.33

FRE) G. SCHWEISTHAL, OE CHICAGO, ILLINOIS, POBATION, OF CHICAGO, ILLINOIS, A

ASSIG-NOR TO STEWART-WARNER COR- CORIORATION O F VIRGINIA.

MECHANICAL .FUEL PUMP Application led December 21, 1981. Serial No. 582,226.

This invention relates to improvements in fuel pumps of the mechanical type 1n which the pumping diaphragm may have a variable discharge stroke in accordance with the delivery pressure, that is, as the delivery pressure in the pumping chamber becomes sufiiciently high to resist the discharge stroke -under the influence of the discharge spring beneath the pumping diaphragm, thefull delivery or discharge stroke of the diaphragm will be prevented. Pumps of this general type are well known and the present-improve ments relate to certain details of the construction. i i

5 The improvements disclosed in the present application relating to the actuating means for the fuel pump are covered by claims 1n a divisional application, Serial No. 627,937,

filed Aug. 8, 1932.

A further object of the present invention is the provision of a discharge or vapor dome `cast integral with the pump casing. With this construction the outlet valve assembly is screw-threadedly secured in the lower end a of the cavity forming the vapor dome.

An additional object of the present invention resides in the improved construction of' the filter screen and the support therefor.

Further and additional features and advantages of the present improvements will be more readily apparent from the following description taken in connection with the attached drawings in which Figure 1 is a side elevationl partially in broken section of the fuel pump;

Figure 2 is a plan view of the fuel pump;

Figure 3 is a vertical section taken on the piane indicated 3-3 in Figure 1;

Figure 4 is a side view of the top part of the pump casing;

Figure 5 is a transverse section taken on the plane indicated 5-5 in Figure 4;

Figure 6 is a longitudinal vertical section plane indicated 6 6 in Figure 2;

Figure 7 is a detail horizontal section taken on the plane indicated 7 7 in Figure 6; Figure Sis a partial vertical section on the plane indicated 8-8 in-Figure 2;

vFigure 9 is a detail view showing Athe pickin section;

Figure 10 is another side elevation of the pick-up stem Figure l1 `is a detail section taken on the plane indicated 11-11 in Figure 10;

igure 12 is a detail horizontal section showing the manner in which the pick-up stein is guided by the pump casing;

Figure 13 is a top view of the pick-up stem;

Figure 14 is a detail plan view of the lever assembly, and

Figure 15 is a detail vertical section of the lever supporting means.

In general the pump construction corresponds to present commercial designs and includes a pump casing made up of a top casing part 10 and a bottom casing part 12. The pair ofcasing parts are clamped together by a series of bolts 14 and the marginal flanges 16 of the upper casing part and 18 of the lower casing part surround recessed portions 20 in the upper casing part and 22 in the lower casing part, there being a flexible pumping diaphragm 2'4 clamped at its marginal edge between the pair of pump casing parts. The top casing part 10 has a lateral up stem in side elevation and the diaphragm extension 26 in the usual manner adapted to have removably secured thereto, on its bottom side, a transparent bowl 28 held in place by the swinging yoke 30 and clamping nut 32. The diaphragm is operated in the usual manner by a lever 34 which is adapted to extend into the engine casing for cam actuation. The pump is of a type in whichk the discharge stroke is variable and produced by the force of a compression spring 36, positioned in the recessed portion 22 of the lower casing part 12 and reacting upwardly upon the pumping diaphragm. The lever imparts a positive suction stroke to the diaphragm. l

The design of the upper casing part 10 is an improvement over prior constructions in that it includes an integrally cast vapor dome chamber 38, the axis of which is concentric with the pumping diaphragm. The threaded outlet connection from the chamber 40 of the dome is shown at 42. In this construction it is necessary to assemble the outlet check valve from the lower side ofthe pump casing part 10, and I have shown a plug 44 which supports the outlet valve;y assembly and which is threaded into the casing part from the lower side. The plug 44 carries a valve seatmember 46, assembledy from the upper side of the plug 44 and Ahaving a beaded lower edge 48 for securing the valve seat member in place. The valve seat member has a central passage 50 in communication with the recessed portion which constitutes the pumping chamber. An outlet check valve 52 seats downwardly upon the valve seat member 46 and is normally pressed to seated position by a spring 54 positioned and held in place by a stamped supporting member 56. The stamped member 56 is in the form of a spider, as shown in Figure 7, and has a plurality of arms 58 held in place by the rim 60 of the plug 44. The spider includes adv 4ditional arms 60 bent downwards to engage an upwardly directed shoulder 62 of the plug 44. The stamped spider also includes a cylindrical portion 64 for receiving and positioning the spring, having an opening 66 at its upper side to permit escape of the fuel therefrom. that uponthe dischargestroke ofthe pumping member, the fuel will-be forced upwardly -past the check valve 52 and through the stampedspider 56 and into the vapor dome chamber 40 from which liquid fuel will flow through the outlet connection and fuel vapor will be trapped in the dome to maintain a constant pressure on the fuel delivered.

The casing part 10 .has a horizontal fuel passage 68 through which the fuel flows into the pumping chamber 20. The passage 68 is in line with the threaded inner connection 70 and the straight bore through the casing part 10 is closed by the plug 72, whereby the fuel is caused to flow downwardly and upwardly around the plug 72. The threaded inlet conncction 70 communicates with a recessed chamber 74 on the lower side of the casing extension 26, as clearly shown in Figures -5 and 6.

The casing extension 26 has an integrally cast valve housing portion76, as shown in Figure 5, which has an internally threaded portion 78 and a valve seat portion 80. The valve seat portion 80 has a vertical flow passage 82. The inlet check valve 84 is assembled through the upper open end of the housing portion 76 and is centrally integral lugs 86`which permit and guide the vertical movement of the valve 84. The valve 84 is pressed to its normal seated position by a spring 88, held in place and positioned by a plug 90 which is threaded into the housing 76. The plug 90 has avertical bore 92 in communication with the passage 68 through an opening 94, whereby the fuel may iow into the passage 68 around the plug 90 or It will therefore be understood,

positioned by through the spring 88. It will benoted-that fuel as it flows upward towards the inlet check valve 84 and comprise a pair of biscuit-shaped filter screen members 96 and 98 clamped together at their marginal portions as at 100 and supported by a stamped spider member 102, which is positioned centrally by a depending shoulder 104 of the housing 76. The s ider has arms 106 extending for clamping y the shoulder of bowl against the gasket 108 which seals the fuel bowl 28 to the extension 26 and the spider 102 includes spring arms 110 which engage the outer walls of the housing portion 76. It will be understood that the recessed chamber 74 or dome tends to maintain a partial vacuum therein during operation which assists in maintaining an even flow of fuel from the source of supply to the pump casing.

The lower casing part has an upstanding cylindrical portion 112 which is surrounded by the discharge spring 36. The cylindrical portion 112 forms a guide bearing for a substantially square-shaped in section pick-up member or diaphragm stem 114, vas clearly shown in Figure 12. The pick-up member 114 is of novel construction and is shown in the detail views of Figures 9, 10, 11, 12 and 13 and comprises a metal stamping provided at its lower end with a box-like formation having a slot 116 between the inwardly directed {ianges 118. The stamping 114 may be initially formed fiat and bent to the shape shown and includes side members 120 and curved ianges 122 for guiding the reciprocable movement of the pick-up member. The u per ends of the side member 120 have inwardly directed flanges 124, defining a central circular opening 126 whereby the flanges or fingers 124 engage the shoulder portion 128of a rivet member 130, which-'serves to clamp the pick-up member to the diaphragm 24. For additionally securing the .pick-up member, vertically directed fingers 132 are provided which engage openings of the cupshaped to the bottom side of the diaphragm. A

metal disk 136 formed to take up the slack of the diaphragm is clamped to the upper side thereof and a washer 138 serves to further strengthen the central portion of the pumping member. The box-like formation at the bottom of the pick-up member is intended to receive the enlarged head 140 of the operating lever which may be introduced through the enlarged opening 142 at the mid-portion of the pick-up member. The enlarged head 140 is adapted to engage a cushion abutment 144 seating in the bottom of the box-like'chamber upon the bottom wall 146.

llO

The lever is supported on the pivot pin 148 which is carried by the lower casing part 12 in a cavity 150 thereof in a novel manner by a stamping member 152. This metal stamping includes arms 154-156 bent around the rectangular portion of the lever 34 and interlocked as at 158. Another pair of arms are bent to extend the entire width of the fianged opening 162, as shown in Figure 3, 'and serve to centrally position'the lever. The arms 16() have openings to receive the pivot pin 148. The stamping 152 also includes an upwardly bent clip 164 which, as

shown in Figure 8, enga-ges one end of the follower spring 166 seated in an obliquely disposed spring chamber 168 formed in the lower body casing 12. The compression spring 166 tends to maintain the thrust receiving end 170 of the lever in engagement with the driving cam.

I claim:

1. In a fuel pump of the diaphragm type a pump casing member adapted to be secure to the upper side of the pumping diaphragm, said casing member having a recessed chamber on its lower side adapted to form a pumping chamber, an integral vapor dome chamber extendin upwardly from said pumping chamber, an an outlet check valve assembly removably secured to the under side of said casino' member to separate' the pumping cham r from the vapor dome chamber.

2. In a fuel pump, a reciprocable pumping diaphragm, a pump casing member adapted to be secured to the upper side of the pumping diaphragm, said pump casing member having an upwardly directed integr-al vapor dome and a recessed pumping chamber on its lower yside and an outlet check valve assembly adapted to be removably secured to the underside of said pump casm member before securing the pumping diaphragm thereto.

3. In a fuel pump, a reciprocable pumping diaphragm, a pump casing member having an integral vapor dome ada ted to be secured `to the upper side of sai um ing diaphragm, said pump casing mem r aving a recessed chamber on the lower side formlng a pumping chamber, a discharge connectlon from saidintegral vapor dome and an outlet check valve assembly compris- 111g a screw-threaded'support ada ted to be removably securedto the lower side of the pump casingmember before securement of said pumping diaphragm, an outlet check valve adapted to seat downwardly upon said supporting member, a spring reacting upon said check valve to normall seat the same and a spider for holdin sai spring in place secured to the upper si e of said supporting member. i

Signed at Chicago, Illinois, this 14th day of December, 1931.

FRED G. SCHWEISTHAL. 

